WO2010000027A1

WO2010000027A1 - Removable implantable battery positioned inside implant coil

Info

Publication number: WO2010000027A1
Application number: PCT/AU2009/000853
Authority: WO
Inventors: Helmut Eder; Dirk Fiedler
Original assignee: Cochlear Limited
Priority date: 2008-07-03
Filing date: 2009-07-02
Publication date: 2010-01-07
Also published as: US8798752B2; US20110208267A1

Abstract

An implantable component of a prosthesis comprising of at least one powered component; at least one antenna coil contained within an electrically insulating surround; and an electrical storage element for powering at least one powered component, the electrical storage element being positionable within a support area of the surround, the support area being at least partially within the area defined by the at least one antenna coil.

Description

REMOVABLE IMPLANTABLE BATTERY POSITIONED

INSIDE IMPLANT COIL

Field of the Invention

The present invention relates to a medical device and in particular to a medical device that relies on use of transcutaneous magnetic induction links, such as cochlear implants or other similarly implanted hearing prosthesis.

Background of the Invention

Auditory prostheses, such as cochlear implants, have typically comprised an external component, such as a sound processor unit, and an implantable component, such as a receiver/stimulator unit. The external component typically comprises a casing, a microphone, a processing circuit that converts detected sounds into coded signals, and a power source. The implantable component receives the coded signals and power from the external component and sends a stimulation signal to an electrode assembly which applies electrical stimulation to the auditory system of the implantee producing a hearing sensation corresponding to the original detected sound.

Communication between the external component and the implantable component can be provided by a radio frequency (RF) magnetic induction link comprising an inductively coupled external antenna coil and an internal implanted antenna coil. This RF link provides transcutaneous transmission of the coded signals to, and also typically from, the implantable component and can also serve to provide power to the implantable component. Implantable components having an onboard rechargeable battery have also been proposed. Such prostheses can utilise more than one type of external component or work together with other external or implantable components.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Summary of the Invention

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

According to a first aspect, the present invention is an implantable component of a prosthesis comprising: at least one powered component; at least one antenna coil contained within an electrically insulating surround; and an electrical storage element for powering said at least one powered component, the electrical storage element being positionable within a support area of the surround, said support area being at least partially within the area defined by the at least one antenna coil.

In this aspect, the electrical storage element can be part of a power source for the at least one powered component of the implantable component. The power source can further comprise a control device.

In this aspect, the power source can also comprise a power source antenna coil.

According to a second aspect, the present invention is an implantable component of a prosthesis comprising: at least one powered component; at least one antenna coil contained within an electrically insulating surround; and a power source for powering the at least one powered component, the power source comprising: an electrical storage element; a control device; and a power source antenna coil; wherein said at least one antenna coil and said power source antenna coil are respectively positioned to form a magnetic induction link for transmitting at least power from the electrical storage element to the at least one powered component.

In this aspect, the electrical storage element can be positioned within a support area of the surround, the support area being at least partially within the area defined by the least one antenna coil.

In both aspects, the support area can be wholly within the area defined by the at least one antenna coil. In a further embodiment, the support area can be centrally positioned within the at least one antenna coil.

Where present in the first aspect and in the second aspect, the control device can monitor and/or control the operation and use of the electrical storage element and the transfer of power from the storage element to the powered component. In addition, the control device can also be suitable for monitoring and/or controlling the charging of the electrical storage element when an external antenna coil is brought into alignment with the power source antenna coil to provide a radio frequency transcutaneous induction link. The control device can have a rectifier, for example an arrangement of at least one diode, for rectifying the current induced in the power source antenna coil.

Where present in the first aspect and in the second aspect, the power source antenna coil and the at least one antenna coil can be positioned to form a magnetic induction link between the respective coils. The magnetic induction link can be used to transmit at least power from the electrical storage element to the at least one powered component.

In one embodiment of both aspects, the electrical storage element can comprise at least one rechargeable battery. The battery can be nickel-based, for example a nickel cadmium (NiCd) battery, a nickel-metal hydride (NiMH) battery, or a nickel zinc (NiZn) battery. The battery can be silver-based, for example a silver oxide-zinc (Ag₂OZn) battery. The battery can be lithium-based, for example a lithium-ion (Li-ion) battery or a lithium-metal battery. Exemplary Li-ion battery materials include lithium cobaltate, lithium manganate, lithium vanadate, lithium iron phosphate, lithium titanate, or mixed oxide or phosphate materials. Any of the above exemplary battery technologies can have a liquid, partially or essentially fully immobilised, or solid-state electrolyte. The whole battery may be comprised entirely of solid-state materials without any added liquids in its final state.

An illustrative example is an all-solid state lithium-metal / LiPON (lithium phosphor- oxynitride) / lithium cobaltate battery core, with appropriate current collectors.

In one embodiment, the battery can have mass or sintered electrodes. In this and other embodiments, the battery can have strongly alkaline electrolyte solutions that may be immobilised or gelified in order to reduce or prevent leakage.

In both aspects, the power source can be removably positioned on the support area of the electrically insulating surround. In one embodiment, the surround can comprise an elastomeric or polymeric member. The member can, for example, be formed of a silicone rubber. The support area can comprise a pocket for receiving the power source. In one embodiment, the pocket can be substantially circular and have a base, an outer wall and a top lip that partially overlies the power source when it is positioned within the pocket.

The windings of the at least one antenna coil of the implantable component can be positioned within the surround at a location outwardly from the pocket. In one embodiment, at least one winding of the said antenna coil can be positioned within the base and/or outer wall of the surround. Leads can extend from the at least one antenna coil to the powered component.

The power source can have an enclosure. The enclosure can be hermetically sealed. The enclosure can be substantially or wholly cylindrical having a bottom wall, a top wall and an outer wall. In one embodiment, the enclosure can have a concave outer wall. In one embodiment, the enclosure can house at least the electrical storage element and the control device. The control device itself can also have a housing. This housing can be suited to preventing ingress of moisture into the control device. The enclosure and/or housing can be comprised wholly or in part of an encapsulant material. The encapsulant can be a suitable elastomeric or polymeric or thermoplastic material. For example, the encapsulant can be parylene or liquid crystal polymer.

In one embodiment, the enclosure of the power source can also house the power source antenna coil. The power source antenna coil can be contained within a relatively electrically insulating member supported within the enclosure. The electrically insulating member can comprise an elastomeric material, for example a silicone rubber. Where the enclosure has a concave outer wall, the electrically insulating member can be supported within the cavity defined by the concave outer wall. The power source antenna coil can comprise one or more, for example three, windings.

The enclosure of the power source can also contain a magnet. In one embodiment, the magnet can be positioned at the centre of the power source. The magnet can be cylindrical in shape but other shapes can be envisaged.

In another embodiment, the enclosure itself can be formed partially or wholly from magnetic material.

The presence of the magnet or the magnetic enclosure allows the at least one antenna coil and/or the power source antenna coil to be aligned appropriately with an external antenna coil that is also held in place by the magnet.

The at least one powered component can be positioned within a housing. The housing can be formed from a biocompatible material, for example, titanium. This housing can in turn be encapsulated in the electrically insulating surround.

In a further embodiment, one or more hermetic and electrically insulated feedthroughs can be provided in the housing. The feedthroughs provide electrical connection between the at least one antenna coil and the at least one powered component within the housing.

The powered component of the implantable component can comprise a receiver/ stimulator unit with the implantable component being part of an auditory prosthesis, such as a cochlear implant. In a further embodiment, the implantable component can comprise a totally implantable auditory prosthesis, such as a totally implantable cochlear implant. In this case, the implantable component may also comprise a microphone, a sound processor, a stimulator/receiver unit, and at least an intracochlear electrode assembly. The implantable component can at least operate for a portion of time without the need for an external component to be mounted on the implantee as the on-board power source provides the necessary power for the device while ever it has sufficient charge.

In another embodiment, the prosthesis can have an external component. The external component can be used to recharge the power source. Still further, it can be used in conjunction with the implantable component to provide a hearing sensation to an implantee. It will be appreciated that a different or the same external component can be used to recharge the power source and work in conjunction with the implantable component to provide the hearing sensation. In one embodiment, the external component can have a microphone for detecting sound, a sound processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil. The receiver/stimulator unit of the implantable component can receive the coded signal transmitted from the sound processor, process the coded signal and output a stimulation signal. The stimulation signal can be output to an electrode assembly, such as an intracochlear electrode assembly. The electrode assembly then delivers electrical stimulation to the auditory nerve of the implantee so producing a hearing sensation corresponding to the original detected sound. The implantable component can work to use the input from the external component when it is present but rely on on-board componentry when the external component is not being used.

The intracochlear electrode assembly can comprise a carrier member having a leading end that is insertable into a cochlea of the implantee and a trailing end. The carrier can be formed of an elastomeric material, for example a silicone rubber material. The carrier member can have a plurality of electrodes mounted thereon. In one embodiment, the electrodes are mounted in a longitudinal array. Each of the electrodes can have at least one wire, for example two, extending from each electrode back towards the trailing end of the carrier member and then through a cable that extends back to the housing of the implantable component.

The carrier can have 22 electrodes. In another embodiment, the carrier can have 30 electrodes. Other numbers of electrodes can be utilised, including less than 20 electrodes, between 20 and 30 electrodes, and more 30 electrodes. The electrodes can be formed from a biocompatible electrically conducting material, such as platinum. In another embodiment, the implantable component can have a second electrode assembly extending from the housing. The second electrode assembly may have one or more electrodes. This electrode assembly can be mounted within or external the cochlea of the implantee.

In one embodiment, the housing of the implantable component can be positioned subcutaneously within a recess in the temporal bone of the implantee.

The present invention allows for relatively more straightforward replacement of an on-board power source of the implantable component if and when required. This can be achieved, for example, by surgically accessing the implantable component, removing the power source from the support area of the surround and replacing it with a new power source. Use of a power source antenna coil to deliver power through a magnetic induction link to the powered component of the implantable component also removes the need for a connector or feedthrough to exist between the power source and the housing of the powered component. This also allows relatively more ready replacement of the power source as there is no need to disconnect a lead extending from the power source to the housing for the powered component. The lack of a connector or feedthrough also improves the hermeticity of the housing of the powered component.

Brief Description of the Drawings

By way of example only, embodiments of the invention are now described with reference to the accompanying drawings:

Fig. 1 is a plan view of one embodiment of an implantable component according to the present invention;

Fig. 2 is a cross-sectional view through lines II-II of Fig. 1;

Fig. 3 is a cross-sectional view of one embodiment of a power source according to the present invention; and

Fig. 4 is a cross-sectional view of another embodiment of a power source according to the present invention. Preferred Mode of Carrying out the Invention

The embodiment of the invention depicted in the drawings is shown as part of a cochlear implant system. It is to be understood that the present invention has application to other implantable prostheses including but not limited to auditory prostheses.

One embodiment of an implantable component according to the present invention is generally depicted as 10 in Fig. 1. The implantable component 10 of the prosthesis has a hermetically sealed titanium housing 11 that contains components and circuitry for operation of the component 10 that require power to operate.

The component 10 also has an antenna coil 12 comprising two platinum or gold windings 13 that are contained within an electrically insulating surround 14. Electrical connection between the componentry of the housing 11 and the antenna coil 12 is made by way of leads 15 that extend to feedthroughs formed in the wall of the housing 11.

Positioned and supported within the area defined by the windings 13 is an on- board power source 16 that can be used to provide power for the componentry within the housing 11.

As depicted in Fig. 2, the power source 16 can be removably positioned in a support area within the electrically insulating surround 14. In the depicted embodiment, the surround 14 comprises an elastomeric or polymeric member, for example, a silicone rubber. The support area as depicted comprises a pocket 17 that receives the power source 16. The depicted pocket 17 is substantially circular and has a base 18, an outer wall 19, and a top lip 21 that partially overlies the power source 16 when it is positioned within the pocket 17. The top lip 21 serves to hold the power source 16 in place but can be readily manipulated to allow the power source 16 to be removed from the pocket 17.

The windings 13 of the at least one antenna coil 12 of the implantable component 10 are positioned within the surround 14 at a location outwardly from the pocket 17. As depicted, at least one winding 13 of the antenna coil 12 can be positioned within the base 18 and/or outer wall 19 of the surround. Examples of power sources are depicted in Figs 3 and 4.

As depicted in Fig. 3, the power source 16 can comprise an enclosure 20 containing an electrical storage element (here a battery 22), a control device 23, and a power source antenna coil 24. The windings 13 of the antenna coil 12 and the power source antenna coil 24 can be respectively positioned to form a magnetic induction link for transmitting at least power from the battery 22 to the componentry within the housing 11.

The control device 23 can have a number of roles. For example, the control device can monitor and/or control the operation and use of the battery 22 and the transfer of power from the battery 22 to the componentry within the housing 11. In addition, the control device 23 can also be suitable for monitoring and/or controlling the charging of the battery 22 when an external antenna coil is brought into alignment with the power source antenna coil 24 to provide a radio frequency transcutaneous induction link for delivery of power to the battery 22. The control device 23 can have a rectifier, for example an arrangement of at least one diode, for rectifying the current induced in the power source antenna coil 24.

The enclosure 20 of the power source 16 can also contain a magnet 25. In the embodiment depicted in Fig. 3, the magnet 25 can be positioned at the centre of the power source 16. The magnet 25 can be cylindrical in shape but other shapes can be envisaged.

In another embodiment depicted in Fig. 4, the enclosure 20a of the power source 16a is itself formed partially or wholly from magnetic material. This allows removal of a separate magnet from the power source 16a and so allows placement of a larger rechargeable battery 22a within the enclosure 20a. It also potentially provides further space for the control device 23 a.

The presence of the magnet 25 or the magnetic enclosure 20a allows the antenna coil 12 and/or the power source antenna coil 24 to be aligned appropriately with an external antenna coil that is also held on, for example, the outside of the head of the implantee by the magnetic force. The battery 22, 22a can comprise at least one rechargeable battery. The battery can be nickel-based, for example a nickel cadmium (NiCd) battery, a nickel-metal hydride (NiMH) battery, or a nickel zinc (NiZn) battery. The battery can be silver- based, for example a silver oxide-zinc (Ag₂OZn) battery. The battery can be lithium- based, for example a lithium-ion (Li-ion) battery or a lithium-metal battery. Exemplary Li-ion battery materials include lithium cobaltate, lithium manganate, lithium vanadate, lithium iron phosphate, lithium titanate, or mixed oxide or phosphate materials.

Any of the above exemplary battery technologies can have a liquid, partially or essentially fully immobilised, or solid-state electrolyte. The whole battery may be comprised entirely of solid-state materials without any added liquids in its final state.

In one embodiment, the battery 22, 22a can have mass or sintered electrodes. In this and other embodiments, the battery 22, 22a can have strongly alkaline electrolyte solutions that may be immobilised or gelifϊed in order to reduce or prevent leakage.

The enclosures 20, 20a of the power sources 16,16a can be hermetically sealed. In one embodiment, the enclosures 20, 20a can be substantially or wholly cylindrical having a bottom wall 31, a top wall 32 and a concave outer wall 33. The control device 23, 23 a itself can also have an outer housing that is capable of preventing ingress of moisture into the control device 23, 23a. The enclosure 20, 20a and/or housing of the control device 23, 23 a can be comprised wholly or in part of a relatively hard biocompatible overmould. While not necessary, the overmould can be partially, substantially or wholly filled with a relatively electrically insulating material. The overmould can be partially or wholly covered with an encapsulant material. The encapsulant can be a suitable elastomeric or polymeric or thermoplastic material. For example, the encapsulant can be parylene or liquid crystal polymer.

As depicted in Figs. 3 and 4, the enclosure 20, 20a of the power source 16, 16a can also house the power source antenna coil 24. The windings of the power source antenna coil 24 can be formed of platinum or gold and are contained within the enclosure 20, 20a. The power source antenna coil 24 can, as depicted, comprise three windings. The antenna coil 24 can be supported by the relatively electrically insulating material within the overmould, when the material is present. As depicted in Fig. 1, the elastomeric surround 14 can extend not just around the antenna coil 12 but also around the housing 11.

The housing 11 of the implantable component 10 contains a receiver/stimulator unit for a cochlear implant. While the component 10 can operate in conjunction with one or more external components, the depicted component because of its on-board power source 16, 16a can also or instead operate in a stand-alone fashion. While not depicted, the component 10 could comprise a totally implantable cochlear implant and have as well an on-board microphone, a speech processor, the stimulator/receiver unit, and at least an intracochlear electrode assembly. The implantable component 10 can at least operate for a portion of time without the need for an external component to be mounted on the implantee as the on-board power source 16, 16a provides the necessary power for the device while ever the power source has sufficient charge.

As described above, it will be appreciated that the component 10 could operate in conjunction with one or more external components. Such an external component could be used to recharge the power source 16, 16a. Still further, it could be used in conjunction with the implantable component 10 to provide a hearing sensation to an implantee. It will be appreciated that a different or the same external component can be used to recharge the power source 16, 16a and work in conjunction with the implantable component 10 to provide the hearing sensation. In one embodiment, the external component can have a microphone for detecting sound, a speech processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil. The receiver/stimulator unit in the housing 11 of the implantable component 10 can receive the coded signal transmitted from the speech processor, process the coded signal and output a stimulation signal. The stimulation signal can be output to an electrode assembly, such as an intracochlear electrode assembly. In the depicted embodiment, the electrode assembly is not depicted for reasons of clarity but will extend from the housing 11 through feedthrough 40. The electrode assembly then delivers electrical stimulation to the auditory nerve of the implantee so producing a hearing sensation corresponding to the original detected sound. The implantable component 10 can use the input from the external component when it is present but rely on the on-board componentry when the external component is not being used. The intracochlear electrode assembly can comprise a carrier member having a leading end that is insertable into a cochlea of the implantee and a trailing end. The carrier can be formed of an elastomeric material, for example a silicone rubber material. The carrier member can have a plurality of electrodes mounted thereon. In one embodiment, the electrodes are mounted in a longitudinal array. Each of the electrodes can have at least one wire, for example two, extending from each electrode back towards the trailing end of the carrier member and then through a cable that extends back to the housing 11 at feedthrough 40 of the implantable component 10.

The carrier can have 22 electrodes. In another embodiment, the carrier can have

30 electrodes. Other numbers of electrodes can be utilised, including less than 20 electrodes, between 20 and 30 electrodes, and more 30 electrodes. The electrodes can be formed from a biocompatible electrically conducting material, such as platinum.

In another embodiment, the implantable component 10 can have a second electrode assembly extending from the housing (not depicted). The second electrode assembly may have one or more electrodes. This electrode assembly can be mounted within or external the cochlea of the implantee.

In one embodiment, the housing of the implantable component 10 can be positioned subcutaneously and, if required, within a recess in the temporal bone of the implantee.

The present invention allows for relatively more straightforward replacement of an on-board power source 16, 16a of the implantable component 10 if and when required. This can be achieved, for example, by surgically accessing the implantable component 10, removing the power source 16, 16a from the pocket 17 of the surround

14 and replacing it with a new power source. Use of a power source antenna coil 24 to deliver power through a magnetic induction link to the componentry in the housing 11 of the implantable component 10 also removes the need for a connector or feedthrough to exist between the power source 16, 16a and the housing 11. This also allows relatively more ready replacement of the power source 16, 16a as there is no need to disconnect a lead extending from the power source 16, 16a to the housing 11. The lack of a connector or feedthrough also improves the hermeticity of the housing 11. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the scope of the invention as broadly described.

The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1CLAIMS:

1. An implantable component of a prosthesis comprising: at least one powered component; at least one antenna coil contained within an electrically insulating surround; and an electrical storage element for powering said at least one powered component, the electrical storage element being positionable within a support area of the surround, said support area being at least partially within the area defined by the at least one antenna coil.

2. The implantable component of claim 1 wherein the electrical storage element is part of a power source for the at least one powered component of the implantable component.

3. The implantable component of claim 2 wherein the power source further comprises a control device.

4. The implantable component of claim 2 or 3 wherein the power source also comprises a power source antenna coil.

5. An implantable component of a prosthesis comprising: at least one powered component; at least one antenna coil contained within an electrically insulating surround; and a power source for powering the at least one powered component, the power source comprising: an electrical storage element; a control device; and a power source antenna coil; wherein said at least one antenna coil and said power source antenna coil are respectively positioned to form a magnetic induction link for transmitting at least power from the electrical storage element to the at least one powered component.

6. The implantable component of claim 5 wherein the electrical storage element is positioned within a support area of the surround, the support area being at least partially within the area defined by the least one antenna coil.

7. The implantable component of any one of claims 1-4 or 6 wherein the support area is wholly within the area defined by the at least one antenna coil.

8. The implantable component of claim 7 wherein the support area is centrally positioned within the at least one antenna coil.

9. The implantable component of claim 3 or any one of claims 5-8 wherein the control device monitors and/or controls the operation and use of the electrical storage element and the transfer of power from the storage element to the powered component.

10. The implantable component of claim 9 wherein the control device is also suitable for monitoring and/or controlling the charging of the electrical storage element when an external antenna coil is brought into alignment with the power source antenna coil to provide a radio frequency transcutaneous induction link.

11. The implantable component of claim 9 or 10 wherein the control device has a rectifier, for example a diode, for rectifying the current induced in the power source antenna coil.

12. The implantable component of claim 4 or 5 wherein the power source antenna coil and the at least one antenna coil are positioned to form a magnetic induction link between the respective coils, the magnetic induction link being able to transmit at least power from the electrical storage element to the at least one powered component.

13. The implantable component of any one of the preceding claims wherein the electrical storage element comprises at least one rechargeable battery.

14. The implantable component of claim 13 wherein the battery is:

- nickel-based, for example a nickel cadmium (NiCd) battery, a nickel- metal hydride (NiMH) battery, or a nickel zinc (NiZn) battery; or - silver-based, for example a silver oxide-zinc (AgOZn) battery; or

- lithium-based, for example a lithium-ion (Li-ion) battery or a lithium-metal battery, for example, a lithium cobaltate, a lithium manganate, a lithium vanadate, or a lithium iron phosphate battery.

15. The implantable component of claim 13 or 14 wherein the battery has mass or sintered electrodes.

16. The implantable component of any one of claims 13-15 wherein the battery has a strongly alkaline electrolyte solution that may be immobilised or gelified in order to reduce or prevent leakage.

17. The implantable component of any one of the preceding claims wherein the electrical storage element is removably positioned on the support area of the electrically insulating surround.

18. The implantable component of claim 2 or 5 wherein the power source is removably positioned on the support area of the electrically insulating surround.

19. The implantable component of claim 17 or 18 wherein the surround comprises an elastomeric or polymeric member.

20. The implantable component of claim 19 wherein the surround is formed of a silicone rubber.

21. The implantable component of any one of claims 18-20 wherein the support area comprises a pocket for receiving the power source.

22. The implantable component of claim 21 wherein the pocket is substantially circular and has a base, an outer wall and a top lip that partially overlies the power source when it is positioned within the pocket.

23. The implantable component of claim 22 wherein the at least one antenna coil of the implantable component is positioned within the surround at a location outwardly from the pocket.

24. The implantable component of claim 23 wherein the at least one antenna has one or more windings and wherein at least one winding of the antenna coil is positioned within the base and/or outer wall of the surround.

25. The implantable component of any one of the preceding claims wherein two or more leads extend from the at least one antenna coil to the powered component.

26. The implantable component of claim 2 or 5 wherein the power source has an enclosure that is hermetically sealed.

27. The implantable component of claim 26 wherein the enclosure has a bottom wall, a top wall and an outer wall.

28. The implantable component of claim 27 wherein the bottom wall and top wall can at least substantially parallel.

29. The implantable component of claim 27 or 28 wherein the enclosure has a concave outer wall.

30. The implantable component of any one of claims 26-29 wherein the enclosure houses at least the electrical storage element and the control device.

31. The implantable component of claim 30 wherein the control device itself also has a housing that prevents ingress of moisture into the control device.

32. The implantable component of any one of claims 26-31 wherein the enclosure and/or the housing of the control device are comprised wholly or in part of an encapsulant material.

33. The implantable component of claim 32 wherein the encapsulant is a biocompatible elastomeric or polymeric material.

34. The implantable component of any one of claims 26-33 wherein the enclosure of the power source houses the power source antenna coil.

35. The implantable component of claim 34 wherein the power source antenna coil is contained within the enclosure.

36. The implantable component of claim 35 when dependent on claim 29 wherein the power source antenna coil is supported within a cavity defined by the concave outer wall.

37. The implantable component of claims 4 or 5 wherein the power source antenna coil comprises one or more, for example three, windings.

38. The implantable component of claim 26 wherein the enclosure of the power source also contains a magnet.

39. The implantable component of claim 38 wherein the magnet is positioned at the centre of the power source.

40. The implantable component of claim 26 wherein the enclosure itself is formed partially or wholly from magnetic material.

41. The implantable component of any one of the preceding claims wherein the at least one powered component is positioned within a housing.

42. The implantable component of claim 41 wherein the housing is formed from a biocompatible material.

43. The implantable component of claim 42 wherein the biocompatible material is titanium.

44. The implantable of any one of claims 41 to 43 wherein the housing is encapsulated in the electrically insulating surround.

45. The implantable component of any one of claims 41 to 44 wherein one or more hermetic and electrically insulated feedthroughs are provided in the housing, the feedthroughs providing electrical connection between the at least one antenna coil and the at least one powered component within the housing.

46. The implantable component of any one of the preceding claims wherein the at least one powered component of the implantable component comprises at least a receiver/stimulator unit with the implantable component being part of an auditory prosthesis.

47. The implantable component of claim 46 wherein the auditory prosthesis is a cochlear implant.

48. The steps, features, integers, compositions and/or compounds disclosed herein or indicated in the specification of this application individually or collectively, and any and all combinations of two or more of said steps or features.